It is necessary to sample the contents of fluid streams delivered through piping networks, such as wastewater within underground pipe. Environmental laws and regulations often require the reporting of sampled concentrations of specific substances in wastewater streams for compliance purposes. Such fluid streams are usually rich in particulates or contaminating matter. Permanent, in-line sampling devices, such as those including sampling ports, are easily disabled because they can become clogged. Permanently established sampling ports may also suffer the corrosive effects, over time, of the fluid stream's constituents. Such sampling devices are also difficult to clean, thus increasing experimental error. Permanent sampling ports may also be impractical if the piping diameter is too large or the piping inaccessible. It may also be desirable, for safety reasons, that human beings not be exposed to the sampled product, which would rule out manual sample collection.
However, sampling at specific locations, such as that provided by the sampling ports, may nonetheless be desired. For example, in a piping network in which several tributary lines join one main line, the performance of a process may best be measured by sampling the various tributary lines at the point they open to the main, before the two streams become mixed. In contrast, though, randomly chosen sampling locations may also be desired. In complicated piping networks, areas of inefficiencies or possible design failures can sometimes be detected by sampling the concentrations of the process stream therein. These areas, or "hot-spots," readily change location as the prevailing process stream conditions change, making fixed sampling ports useless.
Robotic sampling devices offer a solution to the problem of obtaining samples in underground piping networks. These devices can be remotely operated and samples taken from specific areas as long as the robotic device can reach those specific locations.
Several engineering problems, however, accompany the use of robotic devices. The devices must be operable in submerged or nearly-submerged conditions. The devices must be able to traverse a variety of terrains within the interior of the piping network containing sedimentation, sludge, and the like. The device must be able to collect a sample from specific but varied locations relative to the device. The device should also be able to store a collected sample, label or identify the sample, automatically clean its sample collection system, and prepare the collection system for another sampling event.